Decide activity by percentage bug?

[david_besson]

[ FlexSim 16.2.1 ]

Hello,

In process flow, I set a "Decide" activity to send tokens to downstream activites by percentage.

But it seems that the distribution is not working correctly. In the model attached for example, the tokens seems to be sent to the first connector 1 point more than the percentage specified.

Is it a bug?

Thanks!

q-pf-decide-by-percentage-bug.fsm

[joerg_vogel_HsH]

If you look into the source code, you find that the distribution has a discrete result range [0..100]. That way is zero a possible result of the range and some items are going to the output port 1. To be exact 1/101 of all items will go to the output port number 1.

[david_besson]

Is it not a little bit pernicious?

[joerg_vogel_HsH]

Maybe, the hint should advise not to use 0 percent as a value.

[cameron_pluim]

I think instead it should be:

double randomnum = uniform(0, 1, stream)*100;

This will allow the decimal percentages, while still giving a value between 0 and 100. Theoretically 0 is still a viable solution, but is much less likely in this scenario.

[philboboADSK · Accepted solution]

Yes, this is a bug. I'll add a note to the development list.

For now, if you change line 8 to

double randomnum = uniform(0, 100, stream); 

then it will behave correctly.